Hey Tommie,
Brake controllers are a pretty universal fit so we'll still have what you need even though your vehicle isn't in our Fitguide. With a Ford E-350 cab and chassis you should be able to use the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C55344 to get a 4-way connector for your lights. This wire harness plugs inline with the factory tail light wiring.
From there you'll need to install the # ETBC7 to get a 7-way socket on the back of your motorhome.... view full answer...